1. Filed of the Invention
The present invention relates to an image recording apparatus for recording an image on a recording medium by using an ink sheet having a plurality of colors of ink, and a method of recording the image. More particularly, the present invention relates to an image recording apparatus and a method thereof, capable of obtaining a multi-color image recording output in accordance with image information or the like. The image recording apparatuses and forms of their methods can be appropriately applied to a computer, CAD, a workstation, a wordprocessor, a personal computer, a facsimile machine, an electronic typewriter, a copying machine, and a printer.
2. Related Background Art
In a conventional image recording apparatus using an ink sheet (parallel-striped coating ink sheet) of repeated stripe-like ink components of a plurality of colors (inks) formed on an ink sheet in a direction perpendicular to an ink sheet feed direction, it is desirable to feed (wind) the ink sheet at almost a constant velocity during image recording. For this purpose, a recording head in a recording unit is generally brought into tight contact with a platen or the like through an ink sheet to perform main ink sheet feed and to remove slackening of the ink sheet through a clutch.
At the time of a change in color of the ink sheet, the ink sheet must be fed independently of a recording sheet. For this purpose, the recording head in the recording unit is generally released from the platen, and the ink sheet is fed by a winding means through a clutch.
The ink sheet generally has a form of a roll and is generally supplied from a supply roll to a winding or take-up roll. In this case, a back tension is applied to the supply roll to prevent unnecessary slackening or the like.
A winding force during a change in color of the ink sheet must exceed a sum of the back tension, a load of the supply roll, and the load of the ink sheet feed path. A large winding force may cause variations in feed precision and contamination of a recorded image (printed image) because such a force adversely affects main feeding during image recording. The winding force using the clutch must fall within a predetermined range and is also influenced by the back tension of the supply roll, and the like.
In order to solve the above problem, a means for bringing a roller or the like into rolling contact with an ink sheet to feed the ink sheet to a location except for a recording unit may be arranged to cause a winding means to wind the ink sheet through a clutch arranged on the roll shaft. However, this arrangement has a complicated structure.
A conventional recording apparatus of this type is arranged to cause a color sensor to detect each bar code of a multi-color ink ribbon. The multi-color ink ribbon is wound while a recording head is kept in a DOWN (i.e., the recording head is kept in contact with the platen through the ink ribbon) state (the ink ribbon is pulled), and the ribbon is fed at a constant velocity (i.e., the ribbon passes by the color sensor) to detect the bar code.
In the conventional arrangement, since the velocity of the ink sheet which passes by the color sensor is kept constant, the recording head is set in the DOWN state and the ink ribbon is wound at the constant velocity, although the ribbon can be wound at a high velocity depending on a winding radius. In order to perform a high-speed winding operation, it is possible to wind the ribbon while the recording head is kept in an UP state. In order to perform direct winding, a traveling velocity of the multi-color ink ribbon is changed from the start of ribbon winding to the end of ribbon winding, and ON and OFF timings (cycles) of the bar codes are not constant, and the colors cannot be detected by the color sensor, undesirably resulting in an operation error.
It is possible to increase a bar code width to eliminate a detection error of the color sensor. In this case, however, a maximum recording range is narrowed.